This study is devoted to the observation of the \(\Lambda _{b}^{0} \to J{\text{/}}\psi \Lambda \phi \) decay using proton-proton (pp) collision data collected at \(\sqrt s = 13\) TeV by the CMS experiment at the Large Hadron Collider in 2018, which corresponds to the integrated luminosity of 60fb^–1. The branching fraction ratio \(\mathcal{B}(\Lambda _{b}^{0} \to J{\text{/}}\psi \Lambda \phi ){\text{/}}\mathcal{B}(\Lambda _{b}^{0} \to \psi (2S)\Lambda )\) = \((8.26 \pm 0.90({\text{stat}}) \pm 0.68({\text{syst}}{\text{.}}) \pm 0.11(\mathcal{B})) \times {{10}^{{ - 2}}}\) was measured; the first uncertainty is statistical, the second is systematic, and the third one reflects the uncertainties in the world-average branching fractions of ϕ and \(\psi (2S)\) decays to reconstructed final states.

这项研究致力于使用收集的质子-质子（pp）碰撞数据观察\（\ Lambda _ {b} ^ {0} \ to J {\ text {/}} \ psi \ Lambda \ phi \）的衰减在2018年大型强子对撞机的CMS实验中，在\（\ sqrt s = 13 \） TeV处，这对应于60fb ^–1的综合光度。分支分数比\（\ mathcal {B}（\ Lambda _ {b} ^ {0} \ to J {\ text {/}} \ psi \ Lambda \ phi）{\ text {/}} \ mathcal {B }（\ Lambda _ {b} ^ {0} \ to \ psi（2S）\ Lambda）\） = \（（8.26 \ pm 0.90（{\ text {stat}}）\ pm 0.68（{\ text {syst }} {\ text {。}}）\ pm 0.11（\ mathcal {B}））\ times {{10} ^ {{-2}}} \）被测量；第一个不确定性是统计性的，第二个是系统性的，第三个不确定性反映了ϕ和\（\ psi（2S）\）衰减到重构最终状态的世界平均分支分数的不确定性。